OSINT is all about to creating actionable intelligence from Open Source Data. Trawling through google searches, google alert emails and rss feeds is not only a tedious process. It's also not a particularly effective use of your time, especially when you may be monitoring numerous targets.
There are an increasing number of 'competitive intelligence' apps that monitor company websites and related news-flow. Yet, the more polished UI and slick marketing com tends to reflect their expensive pricing structures.
Fortunately, there are a number of free and open source webpage monitoring apps that might not have the flashy UI and slick marketing but have some great functionality.

Change Detection.com
ChangeDetection.com might not be a bit of un ugly duckling and a touch clunky but it does the job. Its a free service that provides page change monitoring and notification services to internet users worldwide. Anyone can use their service to monitor any website page for changes. They have been providing this service for free since 1999!
I use this service to monitor changes to the MAS (Monetary Authority of Singapore) Investor Alert watchlist
Anytime there are amendments to the MAS watchlist page, I receive an email notification which links back to the site highlighting all the changes as shown in the screenshot below.

Page Monitor
Page Monitor which was a completely free service is now Visual Ping which has become quite a polished app.
I’ve left it in the list as it still has a reasonable ‘free’ tier. The monitoring service is provided via its chrome extension

ChangeMon lets you monitor any HTML page or RSS feed for changes. You can choose to be notified when a word/phrase is either added or removed from a web page, or you can choose to monitor only a specific part of a web page by visually selecting a target element. This service is completely free and doesn't require you to sign up for an

Update Scanner
Update Scanner is a Firefox add-on that monitors web pages for updates. I rarely use Firefox so haven’t run the extension myself but it does look pretty cool.

Delta Feed
DeltaFeed allows you to monitor webpages and receive any changes on a website as a News Feed in your inbox. Its free service provides up-to 15 monitoring's updated every 6 hours. If changes/news/additions are found on the target site, snippets with changes of the page are delivered as a specialised newsfeed.